Primary objectives of this work are to examine current knowledge in the field of chemical carcinogenesis and related fields and to identify criteria for the evaluation of carcinogenic effects of chemical and physical agents. Risk assessment methods are reviewed with consideration of qualitative and quantitative criteria. Laboratory methods and biological models for the detection and quantification of the carcinogenic activity of chemicals are examined and evaluated, with particular emphasis on animal models and in vitro models for carcinogenesis studies. Data on the experimental design and results of carcinogenicity bioassays of mineral oils (petroleum lubricating base oils and derived products) were analyzed and reviewed for inclusion in the Monograph series of the International Agency for Research on Cancer on the Evaluation of the Carcinogenic Risk of Chemicals to Humans.